One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,14,17)(11,18,20,15)(12,16,13,22)(19,24,21,23)(25,26)(27,33)(28,39)(29,34)(30,35)(31,37)(32,36)(38,40)(1,2)(3,7)(4,6)(5,8)(9,11,14,20)(10,15,17,18)(12,21,13,19)(16,24,22,23)(25,27,32,29)(26,33,36,34)(28,37,40,35)(30,39,31,38)(1,3)(2,5)(4,8)(6,7)(25,28,31,34,32,40,30,33)(26,29,35,39,36,27,37,38)(2,6)(3,8)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(25,29,32,27)(26,34,36,33)(28,35,40,37)(30,38,31,39)(2,6)(5,7)(9,13,14,12)(10,16,17,22)(11,19,20,21)(15,24,18,23)(25,30,32,31)(26,35,36,37)(27,38,29,39)(28,33,40,34)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.